/**
 * The hex of a base64url SHA-256 hash, or `undefined`. The function returns `undefined` if
 * `value` is not a string, or if the strict decoder does not decode it to 32 bytes. The
 * strict decoder refuses `=` padding, letters outside the base64url alphabet, and non-zero
 * pad bits (RFC 4648 Section 3.5).
 * @param {unknown} value The base64url text, with no padding.
 * @returns {string | undefined} The hex of the 32 decoded bytes, or `undefined`.
 */
export declare function base64UrlHashHex(value: unknown): string | undefined;
/**
 * The hex of the decoded `id` of an SMT proof, or `undefined`. The function returns
 * `undefined` if `proof` is not an object, or if its `id` is not a base64url SHA-256 hash
 * (see {@link base64UrlHashHex}).
 * @param {unknown} proof The SMT proof.
 * @returns {string | undefined} The hex of the decoded `id`, or `undefined`.
 */
export declare function smtProofRootHex(proof: unknown): string | undefined;
/**
 * True if `value` is base64url text, with or without `=` padding, whose last letter has
 * non-zero pad bits (RFC 4648 Section 3.5). A lenient decoder ignores these bits and gets
 * the same bytes as from the text with zero pad bits. The strict decoder refuses the text.
 * The function does not decode the text.
 * @param {unknown} value The text to check.
 * @returns {boolean} True only for base64url text with non-zero pad bits.
 */
export declare function hasNonZeroPadBits(value: unknown): boolean;
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